The invention relates to fuel filter water separators for internal combustion engines, usually diesel engines, and more particularly to a drain valve therefor.
Diesel fuel tends to contain relatively high levels of impurities such as particulate matter and water, as compared to corresponding levels in other liquid hydrocarbon fuels. As a consequence, diesel fuel typically needs to be filtered before injecting the diesel fuel into the engine. The concern over the levels of particulate matter and water in the diesel fuel are significant due to the problems which can be caused. Particulate matter can clog fuel lines and fuel injectors and cause deposits to be formed in the combustion chamber. When water-laden diesel fuel is run through a fuel system and engine, the presence of the water can cause the fuel injection system to malfunction due to rust, corrosion, deposits, etc. Excessive levels of water may lead to catastrophic injector nozzle failure due to the effects of steam expansion and/or lubricity effects.
Fuel filter water separators are known in the prior art for filtering the particulate matter and removing the water. Fuel filter water separators with a drain valve for periodically draining the collected water are also known in the prior art, for example as shown in U.S. Pat. No. 5,855,772, incorporated herein by reference.
The present invention provides an improved drain valve for a fuel filter water separator. The fuel filter water separator has a housing defining a water collection space and a vent space. The housing has a wall with a drain opening therethrough for draining water from the water collection space, and a vent opening therethrough and permitting incoming air to replace outgoing water. The engine has a running condition wherein the fuel filter water separator is pressurized, and an off condition wherein the fuel filter water separator is not pressurized. The drain valve includes a housing mounted to the fuel filter water separator housing and having a first port mating with the vent opening, a second port mating with the drain opening, and a third port. An actuator member in the drain valve housing is actuatable between a closed position blocking communication of the first port with the third port and blocking communication of the second port with the third port. The actuator member in the drain valve housing is actuatable to an open position providing communication of the first port with the third port and providing communication of the second port with the third port. In a typical situation, when the operator sees an indication that water is present, he turns off the engine, thus depressurizing the fuel filter water separator, and opens the drain valve by actuating the actuator member to the open position, and collected water and vent air each flow through the noted third port, but in opposite directions, i.e., if the operator opens the drain valve during the off condition of the engine with the fuel filter water separator not pressurized, the first port draws air through the vent passage from around the drain stream of collected water flowing in the opposite direction in the third port. In one embodiment, if the actuator member of the drain valve is actuated to the open position when the engine is in the running condition and providing pressurized fuel at the noted vent opening, then fuel spray from the vent opening and collected water from the drain opening of the fuel filter water separator housing each flow through the noted third port in the same direction, i.e. if the operator opens the drain valve during the running condition of the engine with the fuel filter water separator pressurized, a pressurized fuel vent stream from the first port joins the drain stream from the second port at the third port and flows in the same direction therethrough.